Currently, in a 3rd generation partnership project (3GPP), a next generation system, which corresponds to a successor of long term evolution (LTE)-advanced as one of fourth generation radio communication systems and is called 5G, has been examined. In the 5G, three use cases including an extended mobile broadband (eMBB), a massive machine type communication (mMTC), and an ultra reliability and low latency communication (URLLC) are mainly assumed.
The URLLC is aimed at realization of a radio communication with low latency and high reliability. In the URLLC, as a specific plan for realization of low latency, introduction of a short transmission time interval (TTI) length (also referred to as a subframe length, a subframe interval, or a transmission time interval), shortening of control latency from packet generation to data transmission, and the like have been examined. In addition, as a specific plan for realization of high reliability in the URLLC, introduction of a coding mode with a low coding rate and a modulation mode for realization of a low bit error rate, utilization of diversity, and the like have been examined.
In addition, in the URLLC, for example, realization of U-plane latency of 1 ms and a packet error rate of, for example, 10{circumflex over ( )}-5 has been examined. Shortening of the TTI length in comparison to a typical packet (for example, a packet of an eMBB traffic) has been examined to realize low latency.
In the 5G, it is considered that the eMBB traffic and a URLLC traffic are mixed in a user equipment. In this case, the TTI length of the URLLC is shorter in comparison to the eMBB, and thus URLLC data may be transmitted in higher frequency in comparison to the eMBB.
Here, in the 5G, as is the case with LTE, it is assumed that a transmission control called hybrid ARQ (HARQ) (refer to Non-Patent Document 1), which efficiently guarantees a packet error that occurs in a radio section at a short control latency time, is performed.